Strategies on energy loss reduction from high-temperature steam for stable hydrogen production using solid-recovered fuel

A high-temperature steam generation system to supply steam to a water electrolysis system was designed and tested using solid-recovered fuel (SRF). The energy loss must be reduced to supply hydrogen production stably, which are conducted by three strategies: (a) using a double pipe, (b) installing a baffle inside the pipe to obstruct steam flow, and (c) bypassing the overflowing steam. Double pipe reduced energy loss by 25% compared to single pipe. Consequently, a heat source with a temperature of 973 K or higher was obtained. In addition, CFD simulation was performed over a temperature range of 373 to 973 K to investigate the change in energy loss with the temperature of the external fluid. When the three baffles were installed inside the double pipe, it reduced heat dissipation approximately 6%. Therefore, installing three or four inner baffles inside the double tube proved to be the most effective method, and it was confirmed that the temperature of the external fluid should be maintained above 573 K. It was concluded that the system using the double pipe with inner baffles can produce approximately 43.8 ton/year of hydrogen when generating high-temperature steam, and the CO₂ emission is reduced to 1.1 ton-CO₂/ton-hydrogen compared to liquefied natural gas.